Exhaust gas-treating devices are usually built by lining up components having different functionalities. For example, an oxidation catalyst, a particle filter, a feed means with an optional mixer, possibly a hydrolysis catalyst, a selective catalytic reduction catalytic converter (SCR catalytic converter) and a blocking catalytic converter are nowadays installed one after another in the exhaust gas flow of an internal combustion engine in a motor vehicle. Unburnt hydrocarbons, hydrogen and carbon monoxide are reacted with oxygen into carbon dioxide and water by the oxidation catalyst in order to extensively free the exhaust gas flow from unburnt hydrocarbons and carbon monoxide. The particle filter filters out soot particles as well as fine dusts that may be present from the exhaust gas of the exhaust gas flow. This particle filter is heated at intervals by heating to the extent that the soot particles retained by the particle filter can react with oxygen to form carbon dioxide. The particle filter is regenerated thereby. A urea-water solution is usually mixed with exhaust gas in the optional mixer via the feed means with an optional mixer, while the water is evaporated at the same time in this case and a fluid, containing very finely dispersed urea or ammonia, is formed. A hydrolysis catalyst may also be used at this point to hydrolyze the urea into ammonia and CO2. The ammonia is needed, in turn, to convert nitrogen oxides possibly formed during the combustion of the fuel in the internal combustion engine on the SCR catalytic converter by selective catalytic reduction (SCR) with ammonia into nitrogen and water. A blocking catalytic converter, which oxidizes excess residues of ammonia from the exhaust gas flow into nitrogen, nitrogen oxides and water, in order to achieve that hardly any residues of ammonia will be released into the environment with the exhaust gas, is usually installed at the end of this lining up of catalytic converters.
In the worst case, this leads to five components in the line, and ceramic catalysts must be mounted at least partially in a metallic housing in four cases. Besides the large space required and the enormous complexity of the overall system, the great heat loss occurring because of the inherently large thermal mass and because of the large surface is counterproductive. Attempts are therefore made even now to combine a plurality of components into multiple components. Thus, a particle filter with an oxidation catalyst coating is now common, in which case the oxidation catalyst coating forms the oxidation catalyst integrated with the particle filter. Furthermore, combinations of hydrolysis, SCR and blocking catalytic converters are known as well. However, there remain nowadays at least three components, which are to be arranged one after another, due to the feed means for the reducing agent.